Conjugation of resveratrol with RGD and KGD derivatives

The reaction between Arg-Gly-Asp (RGD) and Lys-Gly-Asp (KGD) derivatives with 3,4′,5-trihydroxy-transstilbene (resveratrol) was investigated. Knowing that resveratrol, RGD as well as KGD analogues inhibit human platelet aggregation in vitro, it was tempting for us to examine whether their coupling products present enhanced biological activity. Here, we report on the synthesis and identification of these coupling products. The N-protected peptides were synthesized by solid phase technique, using the 2-chlorotrityl-chloride resin, by the method of carbodiimides. Coupling reactions with resveratrol took place in solution using N,N-dicyclohexylcarbodiimide (DCC) as coupling reagent and 4-dimethylaminopyridine (DMAP) as catalyst. The reaction products were purified by reversed phase HPLC and identified by ESI-MS. The mono-esterified resveratrol derivative was the main (or only) reaction product, whereas the di- and the tri-ester (to a less extent) formation was noticed in some cases.